System.Classes.TComponent.QueryInterface
Delphi
function QueryInterface(const IID: TGUID; out Obj): HResult; virtual; stdcall;
C++
virtual HRESULT __stdcall QueryInterface(const GUID &IID, /* out */ void *Obj);
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| function | protected | System.Classes.pas System.Classes.hpp |
System.Classes | TComponent |
Description
Returns a reference to a specified interface if the current component supports that interface.
QueryInterface checks whether the component supports the interface specified by IID and, if so, returns a reference to that interface as the Obj parameter. If the component does not support the interface, the Obj parameter returns nil (Delphi) or NULL (C++).
QueryInterface returns the S_OK execution code on success. HResult type
defines the following execution codes: S_OK, S_FALSE, E_NOINTERFACE, E_UNEXPECTED, and E_NOTIMPL.
Note: For components that act as COM object wrappers, QueryInterface calls the QueryInterface method of the internal COM object.